Solomon William KAMUGASA Development and validation of an absolute Frequency Scanning Interferometry (FSI) network TECHNICAL PROGRESS Solomon William KAMUGASA 2nd PACMAN Supervisory Board, CERN 25/09/2015

Project goals Realise absolute distance measurements with FSI between 2 points of interest. Absolute Multiline To provide a portable alternative to CMM that can cope with larger measurement volumes. 3D coordinates High accuracy Reliability Role in PACMAN Fiducialisation Scale for µ-triangulation Methodology: Simulations Development of suitable prototypes Calibration, comparison tests, validation, extrapolation

Absolute distance realisation First prototype Why a sphere? Fibre tip w.r.t sphere centre can be determined accurately Absolute distances in different directions from same point Use existing reflector supports CMM & µ-triangulation measurable Properties Aluminium (not very stable) 1.5 inch diameter 7-9µm sphericity Collimator glued in place

Global Relative Redundancy (GRR)   For uniform network strength, local reliability ZI should be close to GRR For well controlled (reliable) network ZI ≥ 25% If GRR < 25%, some ZI values < 25% 4 FSI stations insufficient for a reliable network

5 station pyramid geometry Best 4 station geometry Square geometry PDOP of 1.5 in both cases Square planar arrangement: Self calibration impossible Tetrahedral arrangement: Stations need to be closer to object than in square arrangement More sensitive to displacement of target Tetrahedral geometry 5 station pyramid geometry Pyramid geometry Target positioned so as to form platonic octahedron Benefits of square geometry (PDOP, less sensitive to displacement) Self calibration PDOP=1.38

Simulations Performed in LGC++ 1000 simulations A priori stdev 5 µm 30 cm 40 cm Measurement object side elevation y x z Target Station 2 m Performed in LGC++ 1000 simulations A priori stdev 5 µm Confidence level 99% Power of the test 90% 5 stations 10 targets Stations arranged so that optimum target position is object COG All targets in on plane (same y coordinates) 4 stations 1 m from object COG, 5th station 2.4 m from COG (in y)

Some simulation results Stations Additional targets Station x,y,z stdev [µm] Target x,y,z stdev [µm] NABLA [µm] Global reliability Fixed N/A 3-5 25-35 1.5733 Free 14-330 4-88 59-160 5.7738 5 (interstation) 1-2 3-4 28-47 1.4702 5 (large volume) 4-9 4-6 28-38 5.4277 4-15 38-227 (Small volume) 3-11 28-39 4.3576 3-8 35-114 Relates to additional targets N=2 Retro-reflector Study N=2 desirable (wide viewing angle) Encouraging results with QDaedalus (it’s early days) Measurable with FSI (ongoing optimisation studies)

Training, Secondment & dissemination Latest Training Measurement uncertainty estimation in engineering applications, CERN (sept) Effective Article and Report Writing, EPFL (Oct-Nov) 3 month secondment (2014) Etalon AG, Braunschweig, DE 1 week technical visit (Nov 15) Liberec TU, Czech metrology institute, Liberec, CZ Past Training Programming French Health & safety Presentations Team building Optics lab AXEL Dissemination Swiss National Report on Geodetic activities 2011-2015 IWAA 2014 LVMC 2014 ETHZ 2014 PACMAN 2015 CLIC 2015 Conference EPMC, Manchester, UK (Nov 2015) Presentation Poster Possibly paper (Measurement Science and Technology)

Next steps 1. Produce prototype in ceramic more stable, measureable by QDaedalus, accurate machining Status: Order placed 2. Acquire 0.5inch N=2 targets Compare performance with SMR Calibrate (compare theoretical & experimental offsets) 3. Finalise simulations Precision, reliability, cost, feasibility 4. Build automated prototype Remove error due to touch, speed up data collection

Thank you for your attention.